1. Field of the Invention
This invention relates to testing apparatus and, more particularly, to apparatus for applying pneumatic pressure to a chamber within a piston to draw a loading fixture and attached lamina from a substrate to measure the bond strength, and the like.
2. Description of the Prior Art
There is a need for a simple, reliable and inexpensive device for measuring the strength of a bond, such as that which is formed between a lamina and its substrate. Illustratively, it is often important to measure the adherence to a surface of a layer of paint, varnish, adhesive, or the like, or even the adherence of a sheet to a cellular core (i.e. "honeycomb" construction). Field testing concrete through measuring the force required to draw concrete anchor from a recent pouring to determine the stability of the structure under examination also is quite important.
Through the years, a number of devices have been proposed to accomplish these purposes. Typically, these proposals suggest cumbersome apparatus that requires many specially manufactured parts. These devices are not only costly, but also are expensive and, nevertheless, quite frequently still fail to provide consistent data. As a general matter, these devices are not suited to field application because their bulk, weight, and lack of adaptability to irregular surfaces tend to prevent their use where there is the greatest need.
Clearly, a simple, inexpensive device to measure bond strengths on irregular surfaces with reproducible results is required.